Pollutants in the flue gas discharged by industries such as pyroelectricity, steel and the like are of many and varied kinds. Purification devices for the flue gas existing in enterprises are mostly directed to governance in SO2. As a major air pollutant, NO also impairs human health, environment, ecology and social economic seriously. Emission standards for flue gas in pyroelectricity, steel and the like that issued have proposed strict demand for the emission of NOR. NO2 and SO2 have similar properties, being acid gases and easy to combine and react with alkaline substances to achieve the purpose of being removed. Since more than 90% of NO in the flue gas is NO, it needs to oxidize NO into NO2 first. There has been a variety of oxidation removal technologies. For example, CN 1923337A discloses a device and a method for ozonization and simultaneous elimination of the multipollutant in boiler smoke gas, wherein the solution of the oxidation and elimination is injecting ozone on the flue of the boiler and then feeding the flue gas treated by ozone into an alkali washing tower to wash. For example, the prior application of the present inventor (CN201310482358.8) relates to a combined desulfuration, denitration, and mercury removal apparatus and method using a semidry process in a circulating fluidized bed (CFB), wherein the solution of the elimination is injecting ozone on the flue before the CFB purification device and then feeding the flue gas treated by ozone into the CFB device to carry out removal reaction. Note that the decomposition rate of O3 becomes strengthened at a temperature higher than 150° C.; therefore, the temperature of the flue gas should not be too high.
Currently, the low-temperature ozonation denitration technology has some advantages in view of removal effect, cost of investment and operating, and becomes a focus in controlling NOx emission concerned by relevant industry or enterprise.
The low-temperature ozonation denitration technology refers to, prior to the flue gas entering into the purification device, injecting ozone into the flue to oxidize NO into NO2 and then entering into subsequent absorbing process. The contacting effect of O3 in the flue and NO in the flue gas directly determines the oxidation efficiency and subsequent absorption effect. Thus, a mixing effect of the two gases becomes a key point for the development of the technology, and accordingly, it becomes a hot spot for the development of the ozone distributor which affects the distribution of the flue gas.
The development of the ozone distributor may learn from the application experience of ammonia injection grid within the former-flue in the denitrification SCR technology reactor device. A main role of the ammonia injection grid is to promote the mixing uniformity of the injected ammonia or ammonia-containing air with the flue gas prior to contacting with the SCR catalyst, and thus improves the reaction efficiency on the SCR catalyst. It is reported that nozzle congestion, low mixing uniformity and the like are common problems during actual application of the ammonia injection grid. For this reason, some specific ammonia injection grids have been developed, for example, the anti-blocking ammonia injection grid disclosed in CN 103480254A and dynamic ammonia injection grid disclosed in CN 203208900U. The key point to design ozone distributor needs to solve the problem of poor mixing effect of the gas flow in laminar flow state and shorten the distance of the flue, wherein oxidation reaction takes place.